Process of forming a large-diameter tubular pile foundation



p 24, 1968 YOSHIKIYO FUKUSHIMA 3,402,559

PROCESS OF FORMING A LARGE-DIAMETER TUBULAR PILE FOUNDATION Filed June 14. 1967 3 Sheets-Sheet 1 its: 1. Fig.2.

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PROCESS QF FORMING A LARGE-DIAMETER TUBULAR PILE FQUNDATION Filed June 14, 1967 3 Sheets-Sheet 5 INVENTOR. Yosmm YO Fi/KUSH/Mfl BY awn/n7 d 6mm United States Patent 3,402,559 PROCESS OF FORMING A LARGE-DIAMETER TUBULAR PILE FOUNDATION Yoshikiyo Fukushima, Tokyo, Japan, assignor to Nippon Concrete Kogyo Kabushiki Kaisha, Tokyo, Japan Filed June 14, 1967, Ser. No. 646,116 Claims priority, application Japan, Sept. 26, 1966, 41/ 62,991 4 Claims. (Cl. 61-52) ABSTRACT OF THE DISCLOSURE A number of tubular concrete sections are formed at the work site one on another in vertically aligned relation to form an integral tubular concrete pile structure, which is let down vertically through the water to reach the bottom ground. Each of the tubular sections has a reinforcement including a set of vertical pipe piles, of concrete or steel, arranged in a circle. Such pipe piles in the sections are securely joined together to form multiplelength pipe piles extending from top to bottom of the pile structure. The tubular sections may be precast.

This invention relates to the forming of pile foundation and has for its object to provide a novel foundation process by which foundations required to withstand heavy loads, for example, bridge piers set in a sea or a river, can be formed easily in short periods of time.

According to the process of the invention, a tubular foundation is fabricated by vertically arranging a mumtude of hollow pie piles, for example, of concrete or steel in a circle, forming a tubular concrete section including the pipe piles as its core, joining with the top end of the piles another set of similar piles in the same circular arrangement, forming a second tubular concrete section including the second set of piles as its core, and repeating the procedure a required number of times to obtain a tubular foundation of a desired axial or vertical length.

For a better understanding of the present invention, description will now be made with reference to the accompanying drawings, which illustrate the various stages of the foundation process embodying the principles of the present invention, and in which:

FIGS. 1 and 1a illustrate two different forms of pipe pile usable in the process of the invention, FIG. 1 representing a vertical axial cross section of a concrete pipe pile reinforced wtih pretensioned tendons or wires while FIG. 1a representing a side elevation, partly in cross section, of a steel pipe pile;

FIG. 2 is a vertical axial cross section of a doublewalled tubular mold in which concrete is placed with the pipe piles vertically arranged in the annular space between the inner and outer walls of the mold;

FIG. 3 is a plan view of same, partly in transverse cross section, taken along the line III-III in FIG. 2;

FIG. 4 is a vertical axial cross section showing a second tubular concrete section formed integral with the first tubular concrete section of FIGS, 2 and 3 by welding the bottom ends of similar pipe piles together with the top ends of the respective pipe piles embedded in the first tubular concrete section and placing concrete in a similar double-walled tubular mold mounted on the first tubular concrete section;

FIGS. 5 and 6 illustrate the different stages of the step of letting down a tubular concrete structure formed to a predetermined length by the previous steps vertically through the water and the muddy deposit to the supporting ground;

FIG. 7 is a vertical axial cross section showing how the precast tubular concrete sections are joined at the work site to obtain a desired length of tubular structure; and

FIG. 8 is a side elevation, partly in section, showing how pressure water is led through the pipe piles to jet out from their bottom ends as the tubular concrete structure of the invention is let down through the underwater muddy deposit to the supporting ground.

Referring to the drawings and first to FIG. 1, there is shown one form of pipe pile usable in the fabrication of foundations according to the present invention which is a prestressed concrete pipe pile including annular end plates of iron 11 and 12 having central openings 11a and 12a, respectively, and a multitude of pretensioned wires 13 extending between the end plates. Another form of pipe pile is shown in FIG. 1a, which is of steel.

In the first step of the inventive process, a number of pipe piles in the form of FIG. 1 or FIG. 1a are vertically arranged in a circle, as shown in FIGS. 2 and 3. Then, tendons are applied to the circular arrangement of pipe piles in a spiral or circumferential fashion and joined together by connecting wires manually or by welding to form a tubular basket-like reinforcement structure including the pipe piles 1. This reinforcement structure is placed in a double-walled tubular mold or form in the annular space between its inner and outer walls 4 and 40, As observed from FIG. 2, the pipe piles 1 in the reinforcement are of such length that their top ends extend above the top of the tubular mold 4-40. Subsequently, concrete 5 is placed in the mold to form a first tubular section A.

In the second step of the process, first, a set of similar pipe piles 1 are arranged, as shown in FIG. 4, on the tubular section A in the same manner as those embedded therein with the bottom end plate 11 of each of the pipe piles placed in contact with the adjacent end plate 12 of the corresponding embedded pipe pile 1 in aligned relation to each other and such adjacent end plates 11 and 12 are Welded together. Transverse and connecting tendons are applied to the second set of pipe piles 1, now integral with the first set, in the same manner as described above with the latter to form another tubular basket-like reinforcement structure. A second tubular double-walled mold 4-40 is mounted on the tubular section A to surround the reinforcement structure and again concrete is placed in the mold to form a second tubular concrete section B integral with and similar to the first section A.

Theprocedure described above is repeated a required number of times to obtain a large-diameter tubular pile structure of a desired length. In this manner, tubular pile structures can be fabricated on land which range in length from about 20 to 30 meters and in diameter from about 3 to 8 meters. One example of such tubular pile structure 6 is shown in FIG. 5, which includes three tubular sections A, B and C.

Description will next be made on the third step of the inventive process with reference to FIGS. 5 and 6, in which step the tubular pile structure 6 is set on the supporting ground at the bottom of a sea or a river by letting down such structure vertically through the water. During this step, when the structure 6 being let down reaches the surface H of the muddly deposit lying below the water surface S before reaching the bottom ground X, as shown in FIG, 5, the structure may be axially extended by substantially the same procedure described hereinbefore.

For example, referring to FIG. 6, tubular sections D and E are the ones connected at the work site with the consecutive top section C or D of the pile structure 6 before the bottom section A of the structure 6 is set in the ground at an appropriate depth as a pile foundation to support a desired superstructure 8.

If necessary, such superstructure 8 can be built on the jacks 7, as shown in FIG. 6. As will be readily noted, the

jacks can serve to help level the superstructure 8 as the tubular pile foundation 6 sinks secularly in the source of seasoning. In this case, when the secular sink has practically ceased, concrete is placed in the region of jacks 7 to complete the foundation work.

Again in the third step, when the tubular pile structure 6 is let down through the muddy deposit H to the supporting ground X, as shown in FIG. 5, the letting down of the structure 6 can be facilitated by expelling the mud at its bottom. As will be readily understood, the sets of pipe piles 1 of prestressed concrete or 1a of steel, embedded in the successive tubular sections A, B and C, are vertically aligned with each other, forming multiple-length pipe piles each defining a continuous hole 10 extending vertically through the tubular pile structure 6, as shown in FIG. 8. Thus, according to the present invention, jets of water can be formed to expel the neighboring mud at the bottom of the descending pile structure 6, as indicated by the arrows in FIG. 8, by feeding pressure water into the holes 10 at their top end.

Further, although the tubular concrete structure, for example, shown in FIG. 4, is fabricated at the work site by the procedure explained with reference to FIGS. 2, 3 and 4, it may also be fabricated by precasting individual tubular concrete sections A and B, each including for reinforcement a number of pipe piles 1 exposed at both top and bottom, as shown in FIG. 7. In use of such precast sections, they are placed one on another in vetrically alignment and the adjoining ends 11 and 12 of the vertically aligned pipe piles are interconnected as by welding. Subsequent ly, an annular joint 30 of concrete is cast between the precast sections A and B, encircling the welded pipe joints, thereby to form an integral concrete structure.

Although a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

What is claimed is:

1. A process of forming a large-diameter tubular pile foundation comprising a first step including the substeps of vertically arranging a set of pipe piles in a circle, applying tendons to the circular arrangement of pipe piles to form a basket-like reinforcement, inserting the reinforcement in the annular space in a double-walled tubular mold, and placing concrete in the mold to form a first tubular section; a second step including the substeps of securely connecting another set of pipe piles with the respective pipe piles embedded in said first tubular section at the top end thereof in aligned abutting relation with each other, applying tendons to the second set of pipe piles to form a basket-like reinforcement, setting up a double-walled tubular mold on the top of said first tubular section in aligned relation thereto and placing concrete in the annular space of the secondmentioned tubular mold to form a second tubular section integral with the first tubular section, and repeating such set of substeps to form further tubular sections to obtain an integral tubular structure of a desired length; and a third. step of setting up said tubular structure in a sea, a river or the like by letting it down vertically through the water surface until it reaches the bottom ground.

2. A process of forming a large-diameter pile foundation as set forth in claim 1, in the third step of which the tubular structure is axially extended as it is let down vertically through the water surface by connecting an additional set of similar pipe piles to thetop of the respective pipe piles extending above the top of said tubular structure, applying tendons to the additional set of pipe piles to form a basket-like reinforcement, setting up a double-walled tubular mold on the top of said tubular structure in aligned relation thereto, inserting the last-mentioned basket-like reinforcement in the annular space in the last-mentioned tubular mold, placing concrete in the latter to form a tubular extension section integral with said tubular structure, and repeating the formation of such tubular extension section a desired number of times to obtain an extended tubular structure reaching the bottom ground.

3. A process of forming a large-diameter tubular pile foundation as set forth in claim 1 in the third step of which pressure water is fed into the set of aligned pipe piles embedded in the tubular structure to jet out at the bottom ends of the pipe piles thereby to expel any neighboring muddy deposit to aid the tubular structure to descend to the bottom ground.

4. A process of forming a large-diameter tubular pile foundation as set forth in claim 2 including a further step of arranging on the top end surface of the extended tubular structure a number of hydraulic jacks operable to keep the level of the superstructure built thereon in spite of any possible secular sink of the tubular structure under the load of the superstructure, and placing concrete about the jacks to set the level of the superstructure when the secular change has practically ceased.

References Cited UNITED STATES PATENTS 1,665,795 4/1928 Sipe 6l46.5

FOREIGN PATENTS 732,494 6/ 1955 Great Britain.

JACOB SHAPIRO, Primary Examiner. 

